You already saw that the action attribute is empty. Yet still you tried to extract something(?) from it -- just to realize that it is in fact empty. Does that surprise you? What did you expect to get from an empty string?

Regexes cannot extract nonexistent characters. An empty string is empty, there's nothing you can do about that.

Yes, an empty action attribute does point to the current URL. So the form target is the same URL you used to access the document.

Why canít I use certain words like "drop" as part of my Security Question answers?
There are certain words used by hackers to try to gain access to systems and manipulate data; therefore, the following words are restricted: "select," "delete," "update," "insert," "drop" and "null".